Fuel injection system



March27, 1962 T. M. BALL ETAL FUEL INJECTION SYSTEM Filed July 50. 1958 3 Sheets-Sheet 1 March 27, 1962 T. M. BALL ETAL 3,026,860

FUEL INJECTION SYSTEM Filed July 30, 1958 3 Sheets-Sheet 2 6/ AZ 95 a "4 6 4% 6 2 Q IIIIII 6 7 1 I 5 24 22 /?2 g j 27 /2 I 1 222 22! 202 I s '9;D K 75 M g 17a 2% ,4 s f 23/ a 3 4 20a 24 23 4a 5 2/4 s 25 250 Z46 I 2g! M- BALL ROBERT E GR/JHHM CLIFTON M. ELLIOTT JOHN w. HURST AND 5 32 MEflRL. 5. NOFTZ.

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March 1962 T. M. BALL ETAL 3,026,860

FUEL INJECTION SYSTEM Filed July 30, 1958 In W i 3 Sheets-Sheet 5 3,026,860 FUEL INJECTHON SYSTEM Thomas M. Ball, Bloomfield Hills, Robert P. Graham, Pontiac, Clifton M. Elliott, Birmingham, John W. Hurst, Royal Oak, and Mearl E. Noftz, Birmingham, Mich, assiguors to Chrysler Corporation, Highland Park, Mich., a corporation of Delaware Filed July 30, 1958, Ser. No. 751,999 23 Claims. (Cl. 123-119) This invention relates to a fuel injection system of the type disclosed in the following related copending applications owned by applicants assignee and having the following filing dates: Clifton M. Elliott, Serial No. 752,000, filed July 30, 1958, now U.S. Patent No. 2,- 957,466; John W. Hurst, Serial No. 752,003, filed July 30, 1958, now US. Patent No. 2,953,021; Clifton M. Elliott, Serial No. 752,004, filed July 30, 1958; and Eugene P. Wise, Serial No. 752,005, filed July 30, 1958. This particular application also relates to basic improvements on the fuel metering systems disclosed in the previously filed Thomas M. Ball application Serial No. 727,423, filed April 9, 1958.

In particular this invention is concerned with improved means for metering fuel to the cylinders of an internal combustion engine in amounts determined by engine operating conditions. The invention is concerned mainly with automotive engines, but, it is anticipated that the disclosed type of fuel metering system may be used on other types of internal combustion engines.

It is conventional in fuel injection systems to supply fuel under pump pressure to a metering system which regulates the fuel flow to a number of fuel injection nozzles in accordance with the engine speed and load requirements. In such systems it is common to meter the fuel to the nozzles through one or more needle valve controlled metering orifices which needle valves are subject to regulation by various atmospheric and engine operating parameters, including speed and load as aforesaid. Among the problems encountered by such systems is the fuel vaporization and cavitation particularly on hot days during conditions of comparatively light load and fuel flow on the downstream side of the fuel metering orifices caused by the pressure drop across said metering orifices. This vapor formation downstream of the metering orifices produces a false fuel pressure, the magnitude of which is variable and depends on the non-measurable factor of the resultant vapor to liquid ratio. Since these metering systems are not equipped to handle variations in this ratio, uneven and non-measurable fuel flow to the nozzles occurs and results in improper fuel-air mixtures and poor engine efficiency and power.

Another problem encountered in these systems is that of maintaining the proper fuel pressure drop across the metering orifices for obtaining a metered fuel supply which is substantially linear over the engine speed range with respect to the air consumption of the engine.

It is an object of this invention to provide a fuel injection system of the aforesaid type which will overcome the foregoing problems.

Another object is to provide a fuel metering unit for a fuel injection system which unit is capable of delivering fuel to said system in amounts relative to engine speed and engine load.

Another object is to provide a fuel injection system capable of utilizing fuel under relatively high pressure by virtue of a novel return flow fuel metering mechanism and a pressure increaser means, which high pressure inhibits fuel vapor formation.

Another object is to provide a fuel inject-ion system capable of purging vapors from the feed fuel particunited States Patent 2 larly at light engine load conditions by supplying an excess of feed fuel to a metering unit which allows a large portion of the feed fuel to recirculate back to the fuel tank.

A further object is to provide an improved automotive fuel injection system having a return fuel flow metering unit and a manually operated accelerator fuel pumping means immersed in the return fuel to be cooled thereby and adapted to pump a portion of the return fuel, which is substantially purged by vapor by virtue of the flow of the return fuel, to the engine as required for acceleration.

Another object is to provide a fuel injection system of the aforegoing character having a load sensor capable of metering fuel to the engine in a substantially linear relationship with respect to air flow to said engine.

Another object is to provide a fuel inject-ion system having a metering means responsive to changes in atmospheric temperature and pressure to adjust the fuel supply to the engine in accordance with these changes.

Another object is to provide a fuel injection system having a speed metering unit utilizing a return flow metering valve comprising a disc type return flow metering member and a mating return flow metering orifice, said valve having a high flow rate capacity with respect to movement of said metering member.

In carrying out this invention a continuous fuel feed conduit connects a fuel supply or tank to the intake manifold of an internal combustion engine. A fuel pump located either in the fuel tank or in the fuel feed conduit pressurizes and pumps a substantially constant volume of fuel through the conduit which volume is in excess of that used by the engine operating at maximum fuel consumption conditions. The pressurized fuel is fed into a fuel supply pressure chamber which forms a part of the fuel feed conduit and which communicates with the tank through a return flow conduit through which conduit the fuel in excess of that required by the engine is returned to the tank. The amount of fuel returned to the tank is determined jointly by a speed and load sensor. The lead sensor operatively communicates with the low pressure portion of the intake manifold through portions of the fuel feed conduit comprising a fuel distribution chamber and nozzle feed conduits, and constantly receives a pressure signal from said manifold which signal is transmitted to a load metering valve located in the fuel feed conduit to control the amount of fuel flowing to the engine in accordance with the pressure drop across the load metering orifice.

air flow to the engine. The load metering valve may be manually adjustable to compensate for irregularities or non-uniformities in different engines using this system. The'speed sensor carries a speed governormeans of the fiyweight type which is operatively connected to a drive port-ion of the engine and responsive to engine speed to adjust a return flow metering valve and regulate thereby the flow of fuel through the return flow conduit to the tank to effectively control the fuel pressure in the fuel supply pressure chamber. The valve may advantageously comprise a return flow metering orifice and a shiftable disc type metering member which member can effectively control the flow across said orifice. The load metering valve of the load sensor is so constructed that the fuel pressure developed in the fuel supply pressure chamber of the speed sensor over the speed range of the engine is sufficient to cause a fuel flow through the load metering valve to the engine which is substantially linear with respect to the air consumption of the engine. The return flow metering valve of the speed sensor is operatively connected to the load metered fuel and adjustable in response to the pressure thereof to further regulate the flow of return fuel from the fuel supply pressure chamber so as to sense and maintain the proper fuel A pressure increaser valve. may bepositionedinthe fuel feed conduit downstream of the load metering orifice to prohibit the metered fuel pressure in the system from dropping below a minimum value. The load metering valve may also be associated with an atmospheric temperature and pressurev sensor which transmits a signal to the load metering valve to adjust it in accordance with said temperature and pressure. An accelerator pump may be immersed in a suitable portion of the return flow conduit to receive return fuel therefrom and discharge it directly to the load metered fuel portion of the fuel feed conduit in response to actuation of the accelerator. The accelerator pump may be substantially surrounded by the return fuel during engineoperation and is cooled thereby.

A basic difference between the systems of the above mentioned application Serial No. 727,423 and the present system is that in the present system only metered fuel flows to the distribution chamber. This is accomplished by placing the speed sensor and the load sensor in series and providing each sensor with a fuel metering means. As a result of this arrangement, the fuel in the, system upstream of the distribution chamber can be maintained at a high pressure relative to the low upstream pressure of the systems in the above mentioned application. The high pressure retards the undesirable formation of fuel vapor in the upstream section of the system. Also, since the return flow conduit in the present system is upstream of the distribution chamber, vapors in the feed fuel arecontinually purged therefrom and are returned to the fuel sourcebefore the fuel enters the distribution chamber.

The use of a piston type load sensor in the improved return flow fuel metering system described herein presents numerous advantages over the diaphragm actuated load sensor of the above application, among them being smaller space requirements, greater piston stroke. with, resultant greater accuracy and range of the load metering needle, and a more linear relationship between the movement of the piston and the manifold pressure changes. The use of the submerged accelerator, pressure increaser, atmosphere temperature and pressure sensor, disc type of return flow metering valve, and adjustable loadsensor linkage .in the combination and arrangement of parts claimed all have definite advantages in the present system and are described in detail below.

Further objects and advantages of this invention will be apparent from the following detailed illustration thereof, reference being had to the accompanying drawings forming a part of this specification wherein like reference characters designate corresponding parts in the several views:

FIGURE 1 is a side elevational view of the fuel injection metering unit;

FIGURE 2 is substantially a vertical longitudinal midsectional view through the unit of FIGURE 1;

FIGURE 3 is a horizontal sectional view of the unit taken on line 33 of FIGURE 1, and rotated counterclockwise 90;

FIGURE 4 is a vertical sectional view of the unit of FIGURE 1 taken along a line and in the direction corresponding to 4-4 of FIGURE 3;

FIGURE 5 is a vertical sectional view of the load sensor of FIGURE 1 taken along a line corresponding to 5--5 of FIGURE 3 in the direction of the arrows with parts broken away to show a section of the load metering orifice of FIGURE 1 taken along a line corresponding to 5A5A of FIGURE 3 in the direction of the arrows;

FIGURE 6 is a view partly in cross section of the general arrangement of the fuel injection system and the engine;

FIGURE 7 is a side elevational view of an automotive distributor-for driving the unit of FIGURE 1;

FIGURE 8 is a diagrammatic partly sectional view of a modification of the unit of FIGURE 1, and

FIGURE 9 represents diagrammatically the hook up of the vehicle accelerator to the throttle and accelerator pump.

Referring in detail to the drawings, and in particular to FIGURES 1 and 2, a fuel injection metering unit designated generally as 10 is provided with a speed sensor designated generally as 12. This speed sensor is conveniently divided into three sections, a speed section 14, an intermediate section 16, and a governor section 18. All three of these sections cooperate simultaneously to adjust the amount of fuel available to the engine in accordance with the fuel requirements of the engine as related to engine speed.

The speed section 14 comprises a housing 20 having a chamber 22 therein to receive a constant volume of fuel supplied under pressure by the pump 24 (FIGURE 6) through the fuel conduit 26. Pump 24 may be electrically driven and its operating speed is independent of engine speed. A fuel filter and vapor separator 28 located in chamber 22 actually receives the fuel initially and after filtering said fuel and separating vapor therefrom discharges the fuel into chamber 22. A return flow metering orifice 36 on housing 2%) provides a passage from chamber 22 to a return fiow conduit 32 which winds throughout the unit 10 and provides numerous chambers as shown in FIGURES 2, 4, and 5. A fuel outlet 34 in housing 20 communicates with an upstream chamber 36 of the load sensor 38 to enable fuel which has not been returned to the fuel source through return flow conduit 32 to flow intochamber 36, (FIGURES 2 and'S).

The intermediate section 16 of the speed sensor 12 is separated from the speed section 14 and the governor section 18 by diaphragms 42 and 44 respectively. This section is provided with a housing 45 having a chamber 46 which communicates with the downstream chamber 48. of the load sensor 38 through a conduit 50 to provide equal fuel pressures in chambers 46 and 48 for a purpose to be explained below.

A chamber 52 in section 16 communicates with an intake manifold chamber 54- of the engine at a point adjacent the throttle valve 56 through conduit 58 (FIGURES 2 and 6 and provides a substantially constant low pressure to the diaphragm 44 when the engine is idling and also provides an increased pressure when the throttle 56 is opened (see FIGURE 6). Conduit 58 also serves to convey fuel passing the seals 64 to the intake manifold. An adjustable air bleed valve 57 communicating with chamber 52 allows air under atmospheric pressure to bleed into said chamber to partially offset the low pressure therein and provides a means for adjusting the idling speed of the engine. A conventional needle valve 60 threadably received in housing 45 and adjustable with respect to the opening of conduit 58 into chamber 52 provides a means to regulate the amount of vacuum transmitted to chamber 52 from the engine manifold in order to further regulate the idling speed of the engine.

Referring again to FIGURE 2, a fuel return flow metering shaft 62 slidably mounted in housing 45 and provided with dirt catching grooves 64 is secured at one end to diaphragm 42 and valve disc 66 by fianges 65 and 68 and rivets 70. Disc 66 is movable with shaft 62 toward orifice 30 to retard the flow of return fuel therethrough to return flow conduit 32. By using a disc type metering valve, a large flow rate can be obtained by relatively small longitudinal movement of the metering shaft 62 which renders the speed sensor more sensitive to speed and pressure variations. A split retaining ring 72 positioned in a circumferential groove 74 in shaft 62 provides a stop to prevent valve disc 66 from moving too far from orifice 30. The other end of shaft 62 abuts flange 75 connected to diaphragm 44 and flange 76 by rivets 78.

Governor section 18 of the speed sensor comprises a housing 80 having a chamber 82 therein communicating with one side of diaphragm 44. The pressure in this chamber is at all times atmospheric and therefore allows a pressure differential to exist across diaphragm 44, since chamber 52 communicates at all times with the low pressure portion of the engine intake manifold. A shaft 84 is rotatably mounted in a sleeve member 81 in housing 81) by ball bearing 86 and bearing surface 87 on sleeve 81 and is keyed for rotation to a flexible drive shaft 88 of the engine distributor 89 (FIGURE 7) by key 90 on shaft 88 and slot 91 in shaft 84. The chamber 92 formed between member 81 and housing 80 serves as a lubricating oil reservoir for ball bearing 86 and bearing surface 87. The oil is introduced into oil cup 94 and flows to said ball bearing and bearing surface through apertures 96 in member, 81.

An end of member 81 is adjustably threadably received in the end of housing 80 and is secured against rotatable movement therein by lock nut 98 threadably received on said end of member 81 and threaded into tight engagement with the end face 100 of housing 89. A nut 102 is threadably received on the end of housing 86 and secures the flexible drive shaft covering 184 to said housing. A fiyweight support 166 is secured to shaft 84 for rotation therewith and pivotally supports flyweights 188 and 118 on bearings 112 and 114 respectively. A sleeve 116 having a flange 118 thereon is mounted on a reduced portion of shaft 84 and is slidable longitudinally of said portion. Slots 126 and 122 in fiyweights S and 110' respectively loosely receive flange 118 which is abutted by shoulders 124 and 126 on flyweights 108 and 118 respectively. A sleeve 128 also longitudinally slidably mounted on said reduced portion of shaft 84 is frictionally secured at one end to the inner race of a ball bearing 136*. Said sleeve 128 mounts on its other end a spring 132 which resiliently urges said sleeves 116 and 128 apart and causes the outer race of ball bearing 130 to abut the heads of rivets 78 with sufiicient force to prevent the outer race from rotating with the inner race and shaft 84. The rotation of shaft 84 in response to the rotation of the flexible drive shaft 88 causes the flyweights 188 and 110 to pivot outwardly from shaft 84 around bearings 112 and 114 respectively, which brings shoulders 124 and 126 of the fiyweights into contact with the flange 118 of sleeve 116 and tends to urge the latter against spring 132. The force transmitted to spring 132 is transmitted through the connected diaphragms to the return flow metering valve disc 66 and tends to move said disc closer to the orifice 30.

It is noted that the force output of a fiyweight governor is, mathematically speaking, proportional to the square of the engine speed. Such a relationship between engine speed and force output, however, does not suffice for supplying fuel to the engine in accordance with the present metering unit since the air consumption of an internal combustion engine with respect to engine speed deviates from a linear relationship. This deviation is particularly noticeable in engines utilizing the ram type manifolds which manifolds are long enough to develop air pulsations therein which pulsations ram additional air into the engine cylinders and cause the engine to require more fuel to offset the leaning effect of the additional air. The relationship therefore between engine speed and governor force output is changed herein by the interposition of spring 132 between sleeves 116 and 128. The spring allows the radius of rotation of the centers of gravity of the flyweights to increase at a faster than normal rate with respect to engine speed over a portion of the speed range and to thereby exert a force on the spring, sleeve 128, and valve shaft 62 which force results in an in crease in fuel flow to the engine over the amount which would flow at that speed in the absence of the spring. Spring 132 may also be designed to have a variable spring rate should it be desired to further vary the output force of the fiywcights. At high speed ranges during which the proportion of air consumption to engine speed decreases due to a reduction in the ram effect at said speeds, the

sleeves 116 and 128 will abut each other and the radius of rotation of the centers of gravity of the flyweight-s will increase with further increases in engine speed at the normal or lower rate. This reduced rate of said radius increase will result in the force output of the governor also increasing at said normal or lower rate with respect to said further increase in engine speed, which reduced rate of force output will result in a flow of fuel to the engine which corresponds more nearly to the linear air consumption of said engine at high speeds.

The specific structure of the load sensor 38 with which the fuel outlet 34 of chamber 22 communicates is shown in FIGURE 3. The load sensor is conveniently divided into three sections for purposes of description. The first section contains the mechanisms which are responsive to changes in manifold pressure and changes in atmospheric conditions to move through suitable linkages the load metering needle 152 with respect to the load metering orifice 154. This first section 150 comprises a cylinder 156 (FIGURES 3 and 5) having a manifold pressure inlet 158 which is operatively connected to the low pressure portion of the engine intake manifold 228. As shown in FIGURE 6, this portion may conveniently be chamber 54 which is downstream of primary throttle valve 56. A piston 16!) having circumferential dirt catching grooves 162 thereon is reciprocably mounted in cylinder 156 and moves upwardly against spring 164 as the intake manifold pressure decreases. The increments of movement of piston are substantially linear with respect to the incremental changes in intake manifold pressure and provide a convenient basis for the design of the load metering needle 15-2 and orifice 154 which design must be such as to obtain desired flow characteristics across orifice 154. The degree of the taper of needle 152, the length of the stroke of piston 160, and the size of orifice 154 are interrelated and are specifically predetermined. These dimensions must be such that the fiow of fuel across orifice 154- can always be adjusted by the load sensor over the speed range of the engine to be substantially linear with respect to the total air flow to the engine as measured by the load sensor. An air vent 159 communicating with conduit 58 in intermediate section 16 of the speed sensor through suitable conduit means 159 cast or drilled in sections 14 and 16 (FIGURES 2 and 3) is provided in the housing of section 150 and allows atmospheric air to flow through slits 161 in the piston 160 and into contact with the exterior of air tight bellows 166 which is nested within the lower portion of piston 160. The low pressure in conduit 58 sucks a continuous flow of air past the bellows 166 which bellows expands lengthwise in response to either a drop in atmospheric pressure or an increase in atmospheric temperature and conversely contracts lengthwise in response to increased atmospheric pressure or decreased atmospheric temperature. Said bellows is secured at its top end to a shell 168 having a plurality of circumferentially spaced slots 170 therein through which slidably extend fingers 172 of plate 174 to which the lower end of bellows 166 is secured. Fingers 172 of plate 174 fit into a groove in the inner wall of piston 160 and are retained therein by split retaining ring 176. A spring 177 normally urges bellows 166 to a contracted condition. A plate 178 is secured to the lower end of shell 168 and carries a socket 180 into which a ball 182 of linkage member 184 is retained. Said linkage member is pivotally secured to arm 186 which is pivotally attached to one end of shaft 188 which shaft is rotatably mounted in the housing of section 150 and extends into chamber 36 of the second section 197 of the load sensor. An arm 190 secured to the other end of shaft 188 is pivotally connected to the load metering needle 152. An arm 192 secured to shaft 188 adjacent the arm 186 is provided with a set screw 194 which extends through slot in arm 186. Arms 186 and 192 may be moved relative to each other when the set screw is loose to adjust the position. of the metering needle 152 with respect to orifice 154 at any desired operating condition of the load sensor, after which the set screw is tightened.

The second section 197 of the load sensor is separated from the first section 150 by suitable walls and fluid tight seals which keep the fiuid in upstream chamber 36 in section 197 from entering section 150. Chamber 36 receives its fuel supply from outlet 34 of chamber 22 of the speed section of the speed sensor which fuel represents the portion of the pumped fuel that is not returned to the fuel tank 198 (FIGURE 6) through the return flow conduit 32. Orifice 154 in the housing of chamber 36 opens into the downstream chamber 48 of the third section 200 of the load sensor. The total effect of the intake manifold pressure and the pressure and temperature of the atmosphere regulates the positioning of the metering needle 152 with respect to orifice 154 to control the flow of fuel therethrough into chamber 48.

Referring to FIGURES 3 and 4, a pressure valve needle 202 positioned in chamber 48 is attached to a diaphragm 204 and is normally urged to a closed position with respect to a fuel port 206 which communicates with the fuel distribution chamber 208 of rosette 210. The combined pressures exerted by the return fuel in conduit 32 and spring 212 urged needle 262 to its normally closed position. These pressures can be overcome by the pressure of the fuel flowing into chamber 48 when a predetermined minimum pressure of fuel in chamber 48 is attained. By establishing this minimum pressure in chamber 43 the formation of vapor in said chamber and in the rest of the system is retarded especially during starting and at slow engine speeds and furthermore the proper flow of fuel through the return flow conduit is insured since the resistance to said flow is overcome by the minimum pressure.

The rosette 210 in FIGURE 4 comprises a body 213 having a plurality of apertures 214 communicating with fuel chamber 203 across orifices 216. A nozzle feed conduit 218 is secured in each said aperture and communicates with a particular portion of the engine intake manifold 220 through a fuel injection nozzle 222 (FIGURE 6). An air conduit 224 has a threaded bushing 225 secured thereto which is threadably secured to body 213 by an intermediate valve carrying nut 227. A lock nut 229 secures the fuel feed conduit retaining plate 231 to the body 213 which plate urges the enlarged portions 233 of the nozzle feed conduits inwardly of the rosette to retain said conduits therein (see FIGURE 5). Conduit 224- may be connected to an air pump 226 which is suitably mounted on the engine block 228 and actuated by the engine camshaft 236 (FIGURE 6). The use of thisair pump is optional, however, a better control over the fuel atomization and dispersion has been obtained by using the pump and its use is advisable. A disc valve 232 normally urged against the inlet air port 234 of said rosette by spring 235 will prevent fuel from flowing into conduit 224 should something happen to the system to cause the fuel in the nozzle feed conduits to back up through air orifices 240. Slots 238 in a valve retaining plate 239 permit the air to fiow into chamber 236 after it passes through port 234. Air chamber 236 communicates with each said aperture 214 across orifices 240. As the air flows across orifices 240 it mixes with the fuel flowing across orifices 216 and forms a liquid in air type dispersion which then fiows through the nozzle feed conduits to the fuel injection nozzles. It is noted that the close proximity of the orifices 216 and 240 prevents collection of liquid fuel on the downstream side of orifice 216. The air orifices 240 should be larger than the fuel orifices 216 since at idle and low fuel consumption conditions the volume of air used greatly exceeds the volume of fuel used.

Referring further to FIGURE 4 a cylinder 24-2 positioned in the return flow conduit 32 slidably receives an accelerator piston 244. Attached to the piston is a shaft 246 which is slidably received in a recess 248 in shaft 259. A groove 252 in shaft 246 slidably receives a-screw 254 which limits the longitudinal movement of the shaft 246 and attached piston 244. An arm 254 is secured to shaft 250 at one end and to shaft 256 at its other end, which shaft 256 is operatively connected to the engine accelerator pedal and rotates clockwise in response to the depression of the pedal to urge shaft 250 against spring 258 to move piston 244 downward. The connection between shaft 256 and the accelerator pedal may be made by any conventional linkage, for example, that of Patent 2,722,206 which connects shaft 34 thereof, corresponding to applicants shaft 256, to the accelerator pedal 18. The type of linkage used is not critical so long as actuation of the accelerator pedal causes downward movement of the accelerator plunger or piston 244. Applicants FIGURE 9 shows diagrammatically how the accelerator pedal 255 may be simultaneously linked to the throttle body 56 or 366 by link 367, and to pump piston 244 by link 257 pivotally connected to arm 259 locked to shaft 256. As piston 244 is moved downward it forces fuel trapped in accelerator chamber 260 through conduit 262 and into chamber 264 where it exerts a force on diaphragm 266. When the pressure exerted on said diaphragm by the accelerator pump reaches a predetermined minimum, needle valve 268 will open and allow accelerator fuel to how directly through conduit 269 to chamber 208 of the rosette for distribution to the fuel injection nozzles. A ball check valve 270 separating the return flow conduit 32 frorn'the accelerator chamber 266 is drawn upwardly from port 272 as piston 244 moves upwardly in response to engine deceleration and allows return fuel to fill chamher 260. The downward movement of piston 244 closes port 272 by forcing ball 270 into contact therewith. It is noted that a spring 274 and return fuel in return flow conduit 32 cooperate to urge diaphragm 266 and attached needle valve 268 to a closed position and establish the minimum pressure on diaphragm 266 which must be overcome by the pressure exerted by piston 244 on accelerator fuel within chamber 260 if acceleration fuel is to flow to the rosette. This accelerator pump is actuated in response to each depression of the accelerator pedal to deliver an extra amount of fuel to the engine while the rest of the fuel distribution system is catching up to the increased engine load condition. Without said pump the rapid increase in air flow into the intake manifold as the throttle is opened would cause a lean air-fuel mixture and result in coughing and spitting of the engine. By placing the accelerator pump in the return flow conduit the fuel which is drawn into the pump is kept cool by the continuous passage of return fuel around the cylinder 242 and in addition, any vapor drawn into said cylinder can bleed out through the top of thepump around the loose fitting piston and back into the return flow conduit. Also the location of the accelerator pump in the return flow conduit provides a means for rendering leakage of the pump inconsequential.

In FIGURE 8 is shown a fuel injection metering system for an internal combustion engine which is basically the same as unit 10 and comprises a speed-sensor 286, a load sensor 282, and an accelerator pump 284. The speed sensor is provided with four housing portions 286, 288, 290, and 292 separated from each other by diaphragms 294, 296, and 298 respectively to provide chambers 300, 302, 304, and 306. Chamber 300 communicates with a fuel tank 308 through conduit 310. A fuel pump 312 in said conduit supplies a constant volume of fuel through filter 314 to chamber 300 during the operation of said engine regardless of the engine load or speed. A return flow metering orifice 316 in said housing portion 286 connects chamber 300 with a return flow conduit 318 which communicates with the inlet check valve 320 of accelerator pump 284. A return fiow metering needle 322 having a tapered point 324 is secured to each of said diaphragms 294, 296, and 298 by suitable grommets 326.

A flyweight support-328 pivotally supports fi-yweights 330 and 332 and is secured to a flexible shaft 334 which is operatively connected to the engine to rotate at a speed directly proportional to engine speed. Flyweights 330 and 332 have projections 336 and 338 respectively thereon which abut the end of needle 322 as said fiyweights pivot outwardly in response to rotation of shaft 334 to urge needle 322 toward orifice 316 against the force applied in the opposite direction against diaphragm 294 by the fuel in chamber 300.

A conduit 34f) connects chamber 308 to the upstream chamber 342 of the load sensor which upstream chamber communicates with a downstream fuel distribution chamber 344 of the load sensor across a load metering orifice 346. A tapered load metering needle 348 positioned in orifice 346 is operatively connected to piston 350 reciprocably mounted in cylinder 352, which cylinder operatively communicates with the low pressure portions of each intake manifold 356 on said engine through conduit 354. Low pressure transmitted through conduit 354 will cause piston 358 to be drawn upwardly against the force of spring 358 to thereby urge the tapered end of needle 348 into closer proximity to the sides of orifice 346 and conversely high pressure in the intake manifolds will tend to urge needle 348 to a more open position with respect to orifice 346. A plurality of nozzle feed conduits 362 extend from chamber 344 of the load sensor to an equal number of fuel injection nozzles 364 located upstream of the throttle valves 366 of the individual intake manifold sections 356. The atomizing air supply to the nozzles 364 is obtained from pump 372 through intakes 378 and 385 and is transmitted to the branch air conduits 374 of said nozzles by a main air conduit 376. Chamber 344 of the load sensor is connected to chamber 382 of the speed sensor by conduit 360 to provide an adjustment of the return flow metering needle 322 with respect to orifice 316 based on the pressure differential existing across orifice 346 of the load sensor.

An idle boost conduit 368 communicates with one of said manifold sections 356 at a point adjacent the edge of the throttle valve 366 of that section and with the chamher 304 of the speed sensor. An air bleed valve 374 in conduit 368 is provided to regulate the pressure transmitted to chamber 384 from said manifold section during idling of the engine in order to regulate thereby the speed of the engine at idling. Under normal idling conditions the pressure in chamber 304 is lower than in chamber 306 which is vented to the atmosphere and said pressure in chamber 306 tends to urge the needle 322 toward orifice 316 to retard the flow of return fuel therethrough and provide a sufficient fuel supply for idling. The requirement of this additional boost to needle 322 is due to the fact that at slow engine speed the fiyweights are not flung outwardly with sutficient force to negate the frictional resistance of the needle 322 to movement.

The accelerator pump 284 having an inlet check valve 328 and an outlet check valve 382 receives fuel through said inlet valve into chamber 384 from which the return fuel continues through the return flow conduit 318 back to the tank. The depression of the accelerator will force piston 386 of said pump 284 downwardly to force fuel through check valve 382 and through conduit 388 directly to the downstream chamber 344 of the load sensor.

It is noted that the series arrangement of conduit 310, chamber 308,, conduit 340, chambers 342 and 344, and conduits 362 provides a continuous fuel feed conduit from the fuel tank to the engine and the fuel metering system may be conveniently described as a fuel feed conduit having a speed metering unit and a load metering unit located therein.

The operation of the fuel injection metering unit 10 will be described in relation to a change in static engine operating conditions, that is, constant engine speed and load. Under said static operating conditions, the combined forces exerted by fiyweights 108 and 110 and the fuel in chamber 46 is balanced by the force exerted by lit the fuel in chamber 22 and the return flow metering disc 66 is maintained stationary at a distance away from orifice 30. In this static condition, the amount of fuel delivered to the rosette distributing chamber 208 is constant and is equal to the constant amount of fuel being delivered to the system by the pump less the constant amount of fuel being returned to the fuel tank through the return fiow conduit 32. If this static condition represents the engine during normal driving speed, the pressure in chamber 52 has no noticeable effect on the operation of the unit and may be disregarded. It is only during idling and very low engine speeds that the pressure differential across diaphragm 44 becomes significant.

As the throttle valve 56 is moved to a more open position by the depression of the engine accelerator 255, an increase in manifold pressure is transmitted to the load sensor piston 168 through conduit 158 and moves said piston down to thereby move the load metering needle 152 to a more open position with respect to the load metering orifice 154. The pressure difierential existing across said orifice is consequently decreased as more fuel is allowed to flow into chamber 48. This decrease in pressure differential causes the flow through orifice 154 to deviate from the desirable fiow which is substantially directly proportional to engine speed. To correct this condition and bring the pressure differential across said orifice up to a value where the flow of fuel therethrough is substantially directly proportional to engine speed, the fuel pressure in speed chamber 22 and load sensor chamber 36 communicating therewith is increased. This increase in pressure is accomplished by moving the return flow metering valve disc 66 closer to orifice 30 by the increased force transmitted by the fiyweights 188 and as the engine speed is increased and by the increased pressure in chamber 46 caused by the increased flow of fuel into the downstream chamber 48 of the load sensor. When the forces transmitted by said fiyweights and the fuel in said chamber 46 once again balance the force transmitted in the opposite direction by the fuel in chamber 22, the flow of fuel through orifice 154 will be substantially directly proportional to the speed of the engine and will correspond to the flow of air into the intake manifold.

The operation of the modification of unit 10 shown in FIGURE 8 is essentially the same as that described above for unit 1.0. The depression of the engine accelerator opens throttle valves 366 which causes an increase in air pressure in each intake manifold branch 356 which pressure increase is transmitted to piston 350 of the load sensor through conduit 354. As piston 350 moves downward, load metering needle 348 moves to a more open position with respect to orifice 346 and allows more fuel to flow into chamber 344. As in unit 10', the pressure differential across the load metering orifice must be raised back to a value which would allow the How of fuel through said orifice to be substantially directly proportional to engine speed. Also as in unit 10, this is accomplished by moving the return flow metering needle 322 to a more restricted position with respect to the return flow metering orifice. In an equivalent manner to unit 10, the forces transmitted by fiyweights 338 and 332 and by the pressure of fuel in speed sensor chamber 302 become balanced against the force of the fuel in speed sensor chamber 380. This balance of forces maintains the return flow metering needle 322 at a distance away from return flow metering orifice 316 which will insure a pressure differential across load metering orifice 346 and allow a flow of fuel therethrough which is substantially directly proportional to engine speed.

We claim:

1. In a fuel injection system for an internal combustion engine, a fuel distribution chamber having a plurality of nozzle feed conduits extending therefrom, a fuel feed conduit communicating with said chamber and with a fuel source, engine speed responsive return fiow metering means and load responsive fuel metering means in series insaid fuel feed conduit and adjustable to vary the flow of fuel to said chamber in response to changes in the speed and load operating conditions respectively of the engine, and said metering means being adapted for operative connection to a drive portion and a manifold portion of said engine respectively to adjust in response to said changes in the operating conditions of said engine.

2. in a fuel injection system for an internal combustion engine, a fuel distribution chamber having a plurality of nozzle feed conduits extending therefrom, a fuel feed conduit communicating with said chamber and with a fuel source, said fuel source adapted to supply fuel to the system under substantially constant pressure, return flow metering means in said fuel feed conduit and adjustable to vary the flow of return fuel to said source, said return flow metering means adapted to be operatively connected to said engine to adjust in response to changes in engine speed, load metering means in said conduit adjustable to vary the flow of fuel into said chamber and adapted to be operatively connected to said engine to adjust in response to changes in engine load.

3. In a fuel injection system for an internal combustion engine, a fuel distribution chamber having a plurality of nozzle feed conduits extending therefrom, a fuel feed conduit communicating with said chamber and with a fuel source, a return flow conduit communicating with said fuel feed conduit and said source, a first adjustable metering means in said return flow conduit for varying the flow of return fuel therethrough, a second adjustable metering means in said fuel feed conduit for varying the flow of fuel to said distribution chamber, said first and second metering means being operatively connected to said engine, one of said means being adjustable in response to changes in engine speed and the other of said means being adjustable in response to changes in engine load.

4. In a fuel injection system for use on an internal combustion engine having a plurality of cylinders, a fuel distribution chamber having a plurality of nozzle feed conduits extending therefrom, each of said conduits being adapted to communicate with a nozzle communicating with a particular cylinder, a fuel feed conduit connecting said chamber to a fuel source, a return flow conduit communicating with said fuel feed conduit and said source, adjustable return flow metering means in said return fiow conduit for varying the flow of return fuel to said source and adapted to be operatively connected to said engine to become adjusted in response to changes in engine speed, load metering means in said fuel conduit located intermediate said chamber and said return flow conduit and adapted to be operatively connected to an intake manifold of said engine and being responsive when so connected to changes in intake manifold pressure to vary the arnount of fuel entering said chamber.

5. In a fuel injection system for use on an internal combustion engine having a plurality of cylinders, a fuel distribution chamber having a plurality of nozzle feed conduits extending therefrom, each of said conduits being adapted to communicate with a nozzle communicating with a particular cylinder, a fuel feed conduit connecting said chamber to a fuel source, a return flow conduit communicating with said chamber and said source, adjustable return flow metering means in said return flow conduit for varying the flow of return fuel and adapted to be operatively connected to said engine to become adjusted in response to changes in engine speed, load metering means in said fuel feed conduit located intermediate said chamber and said return flow conduit and adapted to be operatively connected to an intake manifold of said engine and being responsive when so connected to changes in intake manifold pressure to vary the amount of fuel entering said chamber, and means connecting said return flow metering means and said distribution chamber to continuously adjust the fuel pressure in said fuel conduit and said chamber to insure a flow of fuel into said chamber at a rate which is a function of engine speed.

6. In a fuel injection system for internal combustion engines, a fuel distribution chamber having a plurality of nozzle feed conduits extending therefrom, each of said conduits being adapted for connection to a single fuel injection nozzle mounted on a particular portion of an engine intake manifold, a load metering orifice in said chamber communicating with a fuel source through a fuel feed conduit, a load metering means adapted to be operatively connected to an intake manifold of an engine and carrying a load metering needle movable toward and away from said load metering orifice to close and open same to regulate the flow of fuel therethrough, said load metering means having means thereon responsive to changes in atmospheric temperature and pressure, and also having means thereon responsive to changes in engine load, a return flow conduit connected to said fuel source and communicating with said fuel feed conduit intermediate said fuel source and said chamber, a return flow metering orifice in said return flow conduit, and a speed sensor carrying a return flow metering needle movable toward and away from said return flow metering orifice to close and open the same, said speed sensor being adapted for connection to said engine and responsive to changes in engine speed to move said needle with respect to said orifice.

7. In a fuel injection system for an internal combustion engine having an intake manifold, a load sensor adapted to be connected to said manifold and having an upstream chamber and a downstream chamber and a load metering orifice interconnecting said chambers, said load sensor carrying a load metering needle movable with respect to said orifice to open and close same in response to intake manifold pressure changes, a speed sensor having an upstream chamber and a downstream chamber separated by a flexible pressure responsive diaphragm, a fuel feed conduit connecting a fuel source, and the upstream chambers of said load sensor and said speed sensor in series, said downstream chambers of said speed sensor and said load sensor communicating with each other through a load metered fuel conduit, a return flow conduit connected to said source and communicating with said upstream section of said speed sensor through a return flow metering orifice, a return flow metering needle carried by said pressure responsive diaphragm and movable with respect to said return flow metering orifice to open and close same, said speed sensor being adapted for connection to said engine and responsive when so connected to changes in engine speed to move said return flow metering needle with respect to said return flow metering orifice.

8. In a fuel injection system for an internal combustion engine having an intake manifold, a fuel distribution chamber communicating with a fuel feed conduit through a load metering orifice, said fuel feed conduit being connected to a fuel source, a pressure responsive load sensor carrying a load metering needle movable with respect to said orifice to vary the flow of fuel therethrough, said load sensor adapted to be connected to said intake manifold of said engine to move said load metering needle toward or away from said fuel metering orifice in response to changes in engine load, a speed sensor having an upstream chamber and a downstream chamber separated by a flexible pressure responsive diaphragm, said upstream chamber being positioned in said fuel feed conduit, a return flow conduit connected to said source and communieating with said upstream chamber of said speed sensor through a return flow metering orifice, a return flow metering needle carried by said pressure responsive diaphragm, said speed sensor being adapted for connection to said engine and responsive to changes in engine speed to move said return flow metering needle with respect to said return flow metering orifice, said downstream chamber of said speed sensor communicating with said fuel distribution chamber to allow the fuel pressure developed in said distribution chamber to exert a force on said diaphragm of said speed sensor tending to urge said return 13 flow metering needle toward said return flow metering orifice against the pressure of the fuel in said upstream chamber of said speed sensor.

9. In a fuel injection system for an internal combustion engine, a fuel distribution chamber having a plurality of nozzle feed conduits extending therefrom, a fuel feed conduit communicating with said chamber and with a fuel source, a return flow conduit communicating with said fuel feed conduit and said source, a first adjustable meter ing means in said return flow conduit for varying the flow of return fuel therethrough, an accelerator means communicating with said return flow conduit and said fuel distribution chamber and manually operative to supply portions of the return fuel to said chamber to facilitate engine acceleration, a second adjustable metering means in said fuel conduit for varying the flow of fuel to said fuel distribution chamber, said first and second metering means being operatively connected to said engine, one of said means being adjustable in response to changes in engine speed and the other of said means being adjustable in response to changes in engine load.

10. In a fuel injection system for use on an internal combustion engine having a plurality of cylinders and an intake manifold communicating therewith, a fuel distribution chamber having a plurality of nozzle feed conduits extending therefrom, each of said conduits being adapted to communicate with a nozzle communicating with a particular cylinder through said intake manifold on said engine, a fuel feed conduit connecting said chamber to a fuel source, a return flow conduit communicating with said fuel conduit and said source, an accelerator fuel pump communicating with said return flow conduit to receive fuel therefrom and with said distribution chamber to discharge fuel thereto, said accelerator pump adapted to be operatively connected to a throttle on said engine to opcrate in response to movements of said throttle, an adjustable return flow metering means in said return flow conduit for varying the fiow of return fuel to said source and adapted to be operatively connected to. said engine to become adjusted in response to changes in engine speed, load metering means in said fuel feed conduit located intermediate said chamber and said return flow conduit and adapted to be operatively connected to the intake manifold of said engine and being responsive, when so connected, to changes in intake manifold pressure to vary the amount of fuel entering said chamber.

11. In a fuel injection system for use on an internal combustion engine having a plurality of cylinders and an intake manifold communicating therewith, a fuel dis tribution chamber having a plurality of nozzle feed conduits extending therefrom, ,each of said conduits being adapted to communicate with a nozzle communicating with a particular cylinder of said engine, a fuel feed conduit connecting said chamber to a fuel source, a return flow conduit communicating with said chamber and said source, an adjustable return flow metering means in said return flow conduit for varying the flow of return fuel and adapted to be operatively connected to said engine to become adjusted in response to changes in engine speed, an accelerator fuel pump positioned in said return flow conduit to receive fuel therefrom and be surrounded thereby, said pump communicating with said distribution chamber through an outlet valve to discharge fuel thereto, said outlet valve being operatively associated with a pressure responsive diaphragm to open and allow fuel to pass to said distribution chamber when the fuel within the pump reaches a predetermined pressure, load metering means in said fuel feed conduit located intermediate said chamber and said return flow conduit and adapted to be operatively connected to the intake manifold of said engine and being responsive, when so connected, to changes in intake manifold pressure to vary the amount of fuel entering said chamber, and means connecting said return flow metering means and said distribution cham- 14 her to continuously adjust the fuel pressures in said fuel feed conduit and said distribution chamber to insure a flow of fuel into said chamber at a rate which is a function of engine speed.

12. In a fuel injection system for use on an internal combustion engine having a plurality of cylinders and an intake manifold communicating therewith, a fuel distribution chamber having a plurality of nozzle feed conduits extending therefrom, each of said conduits being adapted to communicate with a nozzle communicating with a particular cylinder on said engine, a fuel feed conduit connecting said chamber to a fuel source, a return flow conduit communicating with said chamber and said source, an adjustable return flow metering means in said return flow conduit for varying the flow of return fuel and adapted to be operatively connected to said engine to become adjusted in response to changes in engine speed, load metering means in said fuel feed conduit located intermediate said chamber and said return flow conduit and adapted to be operatively connected to the intake manifold of said engine and being responsive, when so connected, to changes in intake manifold pressure to vary the amount of fuel entering said chamber, pressure increasing means in said fuel feed conduit interposed between said load metering means and said chamber, said pressure increasing means being adapted to allow metered fuel to pass to said chamber when said metered fuel reaches a predetermined pressure, and a load metered fuel conduit connecting said return flow metering means and said distribution chamber to continuously adjust the fuel pressures in said fuel feed conduit and said chamber to insure a flow of fuel into said chamber at a rate which is proportional to engine speed.

13. In a fuel injection system for an internal combustion engine having an intake manifold, a fuel distribution chamber having a plurality of nozzle feed conduits extending therefrom, each of said conduits being adapted for connection to a particular fuel injection nozzle mounted on a particular portion of said engine intake manifold, a load metering orifice on said chamber communicating with a fuel source through a feed conduit, a pressure responsive load sensor carrying a load metering needle which is movable toward and away from said load metering orifice to close and open same respectively, said load sensor adapted to be operatively connected to the intake manifold of said engine and being responsive to changes in manifold pressure to move said load metering needle with respect to said load metering orifice, a return flow conduit connected to said fuel source and communicating with said fuel feed conduit intermediate said fuel source and said chamber, a return fiow metering orifice in said return flow conduit, and a speed sensor carrying a return flow metering member having a fiat disc shaped end movable toward and away from said orifice to close and open the same respectively, said speed sensor being adapted for connection to said engine and responsive to changes in engine speed to move said return flow metering member with respect to said orifice.

14. In a fuel injection system for use on an internal combustion engine having a plurality of cylinders and an intake manifold communicating therewith, a fuel distribution chamber having a plurality of nozzle feed conduits extending therefrom, each of said conduits being adapted to communicate with a nozzle communicating with a particular cylinder, a fuel feed conduit connecting said chamber to a fuel source, a return flow conduit communicating with said chamber and said source, an adjustable return flow metering means in said return flow conduit for varying the flow of return fuel and adapted to be operatively connected to said engine to become adjusted in response to changes in engine speed, load metering means in said fuel feed conduit located intermediate said chamber and said return flow conduit and adapted to be operatively connected to the intake manifold of said engine and being responsive when so connected to changes aozasao 13 in intake manifold pressure to vary the amount of fuel entering said chamber, said load metering means comprising a load metering member linked to a movable piston for movement therewith with respect to a load metering orifice positioned between said chamber and said fuel feed conduit, said piston being slidable in a housing in response to manifold pressure transmitted into said housing, and a load metered fuel conduit connecting said return flow metering means and said distribution chamber to continuously adjust the fuel pressures in said fuel feed conduit and said chamber to insure a flow of fuel into said chamber at a rate which is a function of engine speed.

15. In a fuel injection system for an internal combustion engine, an intake manifold connected to said engine, said manifold having a central chamber mounting a throttle valve therein, a plurality of manifold branches extending from said central chamber and communicating with separate cylinders of said engine, a plurality of fuel injection nozzles mounted on separate ones of said manifold branches, a fuel distribution chamber having a plurality of nozzle feed conduits extending therefrom and communicating with separate ones of said fuel injection nozzles, a fuel feed conduit connecting said distribution chamber to the outlet of a fuel source, a return flow conduit communicating with said fuel feed conduit through a return flow metering orifice and connecting to said fuel source, a load sensor communicating with said central chamber of said manifold downstream of said throttle valve, said load sensor being positioned on said fuel feed conduit between said return flow conduit and said distribution chamber and responsive to changes in engine load to vary the fuel flow into said distribution chamber, a speed sensor in said fuel conduit having a return fiow metering needle carried by a flexible diaphragm, said needle being movable with respect to said return flow metering orifice to regulate the fiow of fuel therethrough, said speed sensor being operatively connected to said engine andbeing responsive to changes in engine speed to move said return flow metering needle and vary the how of fuel through said return flow conduit, said distribution chamber and said flexible diaphragm of said speed sensor being operatively connected through a load metered fuel conduit so that the pressure of the fuel in said distribution chamber is transmitted to said speed sensor to regulate the position of said needle with respect to said return flow orifice and provide a flow of fuel into said distribution chamber at a rate proportional to engine speed.

16. In afuel injection system for an internal combustion engine having an intake manifold, a fuel distribution chamber having aplurality of nozzle feed conduits eX- tendingtherefrom, each said conduit being adapted for connection to a single fuel injection nozzle mounted on a particular portion of said engine intake manifold, a load metering orifice connecting said chamber with a fuel source, a-load sensor having a load metering needle movable toward and awayfrom said fuel metering orifice to demand open the same to regulate the flow of fuel thcrethrough, an adjustable linkage connecting said needle with said load sensor, said load sensor having means thereon responsive to changes in atmospheric temperature and pressure, said load sensor also having piston means thereon responsive to changes in engine load and adapted to be operatively connected to the engine intake manifold, a return flow conduit connected to said fuel source and said chamber, a return flow metering orifice in said return flow conduit, and a speed sensor carrying a return fiow metering disc shiftable with respect to said return flow metering orifice to-regulate the flow of fuel therethrough, said speed sensor being adapted for connection to said engine and responsive to changes in engine speed to shift said disc with respect to said return flow metering orifice, an accelerator pump submerged in said return flow conduit and responsive to engine accelerator movement to provide the engine with additional fuel from saidreturnfiowconduit, and a pressure increasing means positioned intermediate said load metering orifice and said distribution chamber and responsive to return fuel pressure to increase the fuel pressure throughout the system.

17. In a fuel injection system for an internal combustion engine, a fuel distribution chamber in communication with said engine for supplying fuel thereto, a fuel feed conduit communicating with said chamber and with a source of fuel, a return flow conduit communicating with said fuel feed conduit at a location upstream of said distribution chamber and also communicating with said source to return fuel thereto, return flow metering means in said fuel feed conduit responsive to the speed of said engine to control the flow of fuel through said return flow conduit to said source, and load metering means in said fuel feed conduit downstream of said return flow metering means and responsive to engine load for controlling the flow of fuel to said distribution chamber.

18. In a fuel injection system for an internal combustion engine, a fuel distribution chamber in communication with said engine for supplying fuel thereto, a fuel feed conduit communicating with said chamber and with a source of fuel, a return flow conduit communicating with said fuel feed conduit at a location upstream of said distribution chamber and also communicating with said source to return fuel thereto, an accelerator pump submerged in said return flow conduit and adapted to be manually operated to supply return flow fuel to said engine for acceleration, return flow metering means in said fuel feed conduit responsive to the speed of said engine for controlling the flow of fuel through said return flow conduit to said source, and load metering means in said fuel feed conduit downstream of said return flow metering means and responsive to engine load to control the flow of fuel to said distribution chamber.

19. In a fuel injection system for an internal combustion engine, a fuel distribution chamber in communication with said engine for supplying fuel thereto, a fuel feed conduit communicating with said chamber and with a source of fuel, a return fiow conduit communicating with said fuel feed conduit at a location upstream of said distribution chamber and also communicating with said source to return fuel thereto, return flow metering means responsive to the speed of said engine for controlling the flow of fuel in said return flow conduit to said source, load metering means in said fuel feed conduit downstream of said return flow metering means and responsive to engine load for controlling the flow of fuel to said distribution chamber, and pressure increasing means in said fuel feed conduit downstream of said load metering means for maintaining the fuel pressure within the system above a minimum value.

20. In a fuel injection system for an internal combustion engine, a fuel distribution chamber in communication with said engine for supplying fuel thereto, a fuel feed conduit communicating with said chamber and with a source of fuel, a return flow conduit communicating with said fuel feed conduit at a location upstream of said distribution chamber and also communicating with said source to return fuel thereto, return flow metering means responsive to the speed of said engine for controlling the flow of fuel in said return flow conduit to said source, and load metering means in said fuel feed conduit downstream of said return flow fuel metering means, said load metering means comprising a load metering member carried by a movable piston operatively connected to the low pressure portion of said engine intake manifold and responsive to engine load for controlling the flow of fuel to said distribution chamber.

21. In a fuel injection system for an internal combustion engine, a fuel distribution chamber in communication with said engine for supplying fuel thereto, a fuel feed conduit communicating with said chamber and with a source of fuel, a return flow conduit communicating with said fuel feed conduit at a location upstream of said distribution chamber and also communicating with said source to return fuel thereto, return flow metering means in said fuel feed conduit responsive to the speed of said engine for controlling the flow of fuel in said return flow conduit to said source, said return flow metering means comprising a flat disc valve operatively connected to a governor means driven from said engine, and load metering means in said fuel feed conduit downstream of said return flow fuel metering means and responsive to engine load for controlling the flow of fuel to said distribution chamber.

22. In a fuel injection system for an internal combustion engine, an intake manifold on said engine, a fuel distribution chamber in communication with said manifold for supplying fuel thereto, a fuel feed conduit communicating with said chamber and with a source of fuel, a return flow conduit communicating with said fuel feed conduit at a location upstream of said distribution chamber and also communicating with said source to return fuel thereto, return flow metering means responsive to the speed of said engine for controlling the flow of fuel in said return flow conduit to said source, and load metering means in said fuel feed conduit downstream of said return flow metering means, said load metering means comprising a metering member carried by a movable piston operatively connected to the low pressure portion of said intake manifold, said metering member being adjustably connected to said movable piston and responsive to engine load for controlling the flow of fuel to said distribution chamber.

23. In a fuel injection system for an internal combustion engine, a fuel distribution chamber in communication with said engine for supplying fuel thereto, a fuel feed conduit communicating with said chamber and with a source of fuel, a return flow conduit communicating with said fuel conduit at a location upstream of said distribution chamber and also communicating with said source to return fuel thereto, return flow metering means responsive to the speed of said engine for controlling the flow of fuel in said return flow conduit to said source, and load metering means carrying a load metering member in said fuel conduit downstream of said return flow metering means and operatively connected to said engine to adjust the position of said metering member in response to changes in engine load, said load metering means having an atmospheric pressure and temperature sensor adapted to adjust in response to changes in atmos pheric pressure and temperature, said adjustments being effective to exert a force on said load metering member to vary the flow of fuel to said distribution chamber.

References Cited in the file of this patent UNITED STATES PATENTS 2,136,959 Winfield Nov. 15, 1938 2,410,773 Chandler Nov. 5, 1946 2,589,788 Fell Mar. 18, 1952 2,623,509 Gold et a]. Dec. 30, 1952 2,673,556 Reggio Mar. 30, 1954 

